Dishwasher detergents incorporate persalts such as perborates and percarbonates for spotless results. To activate these bleaching agents and in order to achieve a satisfactory bleaching effect at wash cycle temperatures of 60° C. or below, dishwasher detergents generally further contain bleach activators or bleach catalysts, and it is particularly the bleach catalysts which have proven to be particularly effective.
Bleach catalysts are preferably incorporated into dishwasher detergents in the form of ready-made granules. This is done not only to increase their storage stability, but also in order to increase homogeneous incorporation of minuscule catalyst quantities into the formulations, in particular in tablet applications.
Bleach catalysts based on various manganese-containing transition metal complexes are described in EP 0 458 397, EP 0 458 398 and EP 0 530 870 for example. Processes for producing bleach catalyst granules are disclosed in EP 0 544 440, WO 95/06710 and WO 2008/069935. The processes described therein typically utilize large volumes of inert materials as carriers and also binders, which may optionally be used in melt form, this procedure including cooling and/or drying steps necessitating the use of additional apparatus such as fluidized bed systems.
Yet the germ-killing effect of bleach catalysts is mostly minor. The performance of bleaching agents in dishwasher detergents is accordingly higher when in the form of a combination of a bleach catalyst with a bleach activator. In this case, the peroxycarboxylic acid formed out of the activator works effectively to augment the bleaching effect of the catalyst. The peroxycarboxylic acid also makes a significant contribution to the germ kill on the ware, improves the odor of the wash liquor and prevents the development of a biofilm in the dishwasher. The combination of bleach catalysts and bleach activators is accordingly sensible to enhance bleach performance and to ensure hygiene when bleaching agents are incorporated into washing and cleaning compositions. Washing and cleaning compositions formulated to include not only the bleach activator such as tetraacetylethylenediamine (TAED), sodium nonanoyloxybenzenesulfonate (NOBS) or decanoyl-oxybenzoic acid (DOBA) but also one or more bleach catalysts are known according to the prior art. EP 0 710 714, for instance, describes a bleach composition comprising TAED, a manganese catalyst and crystalline sheet-silicate. These components are incorporated into the laundry detergent formulation as separate particles, but not in the form of a unitary co-granule.
The use of activators and catalysts as separate particles or granules, however, has disadvantages which may have adverse repercussions for bleaching performance. The persalt and/or the hydrogen peroxide released therefrom react with the activator and the catalyst in concurrent reactions. If the catalyst granule is quicker to dissolve than the activator granule, then the persalt will already have been consumed before it is able to react with the activator. The reverse case is analogous. Co-granules as between activators and catalysts are further advantageous to ensure homogeneous distribution of the two components throughout the detergent and to save space in the formulation. A saving is also achieved in the costs of production, since only one co-granule has to be produced instead of two different granules.
WO 03/093405 describes co-granules consisting of a bleach catalyst, a bleach activator and, optionally, a coating. As shown in Example 1, a manganese(II) complex, a TAED powder and a tallow fatty alcohol ethoxylate (Genapol® T500, Clariant) are mixed in a Lödige mixer at 40 to 50° C. and then pressed by an extruder into noodle-shaped granules. Preferred bleach catalysts for producing such co-granules are metal complexes with macrocyclic cross-bridged ligands as described in WO 01/64826 and WO 98/39098. These are notable for particularly good chemical stability.
WO 2010/115581 describes co-granules containing a) one or more bleach activators, b) one or more bleach catalysts and c) at least 5 wt % of one or more organic acids. Fatty acids, alcohol ethoxylates or polymers are referred to as possible binders. Judging by the examples, the preferred binder is Genapol® T500.
A multiplicity of the bleach catalysts referred to in WO 2010/115581, in particular manganese salts, are accordingly convertible into storage-stable odorless co-granules suitable for use in washing and cleaning compositions.
Surprisingly, however, co-granules consisting of TAED, [MnIV2(μ-O)3(Me-TACN) 2](PF6)2.H2O and Genapol® T500 and obtained as taught in WO 03/093405 or WO 2010/11558 are found to have a distinct amine odor after a certain storage period. They are accordingly unsuitable for any commercial use in household products. It is believed that at least a small proportion of the manganese complex decomposes during co-granule production and/or storage, releasing the ligand trimethyltriazacyclononane (TACN), which has a pronounced amine-type odor.